linux-kernel - Re: [PATCH v3] drm/msm/dpu: always program DSC active bits

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Message-ID: <c2c0567a-8205-510d-bc0d-35b28dd64f70@linaro.org>
Date:   Thu, 20 Apr 2023 17:03:33 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Marijn Suijten <marijn.suijten@...ainline.org>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc:     robdclark@...il.com, sean@...rly.run, swboyd@...omium.org,
        dianders@...omium.org, vkoul@...nel.org, daniel@...ll.ch,
        airlied@...il.com, agross@...nel.org, andersson@...nel.org,
        quic_abhinavk@...cinc.com, quic_sbillaka@...cinc.com,
        freedreno@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] drm/msm/dpu: always program DSC active bits

On 15/04/2023 02:02, Marijn Suijten wrote:
> On 2023-04-14 09:46:17, Kuogee Hsieh wrote:
>> In current code, the dsc active bits are set only if the cfg->dsc is set.
> 
> This is the old sentence from v1 again, did you accidentally send the
> wrong patch as the improvements from v2 are missing?
> 
>> However, for displays which are hot-pluggable, there can be a use-case
>> of disconnecting a DSC supported sink and connecting a non-DSC sink.
>>
>> For those cases we need to clear DSC active bits during teardown.
> 
> At least teardown is one word again, v2 had "tear down" which is wrong.
> 
>> As discuss at [1], clear DSC active bit will handled at reset_intf_cfg()
> 
> discussed* as pointed out by Dmitry, and make it clear that this is
> about clearing CTL_DSC_ACTIVE (and CTL_DSC_FLUSH?) specifically.  Once
> that is moved to reset_intf_cfg(), this patch should be reverted as
> there is no need to write the registers once again when cfg->dsc equals
> 0.

Kuogee, can we please get a proper v4? With all the relevant changes 
from v2, with the changelog, etc.

Otherwise the present Reviewed-by tags are just incorrect.

> 
> - Marijn
> 
>> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
>> Fixes: 77f6da90487c ("drm/msm/disp/dpu1: Add DSC support in hw_ctl")
>> Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
>> Reviewed-by: Marijn Suijten <marijn.suijten@...ainline.org>
>>
>> [1] https://lore.kernel.org/linux-arm-msm/ec045d6b-4ffd-0f8c-4011-8db45edc6978@quicinc.com/
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c | 7 +++----
>>   1 file changed, 3 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
>> index bbdc95c..88e4efe 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
>> @@ -541,10 +541,9 @@ static void dpu_hw_ctl_intf_cfg_v1(struct dpu_hw_ctl *ctx,
>>   	if (cfg->merge_3d)
>>   		DPU_REG_WRITE(c, CTL_MERGE_3D_ACTIVE,
>>   			      BIT(cfg->merge_3d - MERGE_3D_0));
>> -	if (cfg->dsc) {
>> -		DPU_REG_WRITE(&ctx->hw, CTL_FLUSH, DSC_IDX);
>> -		DPU_REG_WRITE(c, CTL_DSC_ACTIVE, cfg->dsc);
>> -	}
>> +
>> +	DPU_REG_WRITE(&ctx->hw, CTL_FLUSH, DSC_IDX);
>> +	DPU_REG_WRITE(c, CTL_DSC_ACTIVE, cfg->dsc);
>>   }
>>   
>>   static void dpu_hw_ctl_intf_cfg(struct dpu_hw_ctl *ctx,
>> -- 
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>>

-- 
With best wishes
Dmitry